The invention relates to a manipulator, comprising at least one grab, driving means for moving the grab with a number of translational and/or rotational degrees of freedom, which number can be chosen, and control means coupled with the driving means for moving the grab along a path determined by at least a beginning position and an ending position and wherein is picked up an object in the beginning position and released in the ending position.
Such a manipulator is generally known. In the prior art manipulator, use is made of a feed-back for each degree of freedom by means of which the arrival of the grab at the desired position in that degree of freedom is signalled. Such a system has necessarily a relatively complicated construction as it requires a certain amount of memory space, while furthermore a certain inertia is inherent in the system.
The invention has for its purpose to engineer a manipulator of the type described in such a way that the memory space to be is minimal, so that the computer system used can be of a relatively simple type.
In order to realize this purpose, the invention provides a manipulator which is characterized in that the control means for each degree of freedom comprises a feedback-free counting unit/memory loadable previously in correspondence with the desired displacement in that degree of freedom in such a way that the driving means for each degree of freedom is only operative during an interval in which the contents of the counting unit/memory are smaller than the loaded counting value while the counting unit is also adapted for counting to the loaded counting value after receiving a starting signal, if desired controlled by a program for a desired loading pattern.
In order to ensure that the system is able to operate with a high speed without having the undesired effect that the end point in a degree of freedom is overshot as a result of mechanical inertia in the system, preference is given to that embodiment in which the control means is adapted to control the driving means in a fast speed mode during the beginning of the counting interval and in a slow speed mode during the end of the counting interval.
In a simple embodiment, the counting value for the slow speed mode may be a fixed value.
In a manipulator in which the objects are conveyed successively along a fixed path, use may be made of detection means such as a light source with a photo cell or a micro switch for providing a starting signal to the control means responsive to the arrival of an object.
The grab or pickup/release means may be provided with a detector such as a micro switch which detects when an object has been picked up and when it has been released.
The grab may be of serveral types such as a spoon, a pair of tongs, a fork-element, a vacuum head or the like. In the English literature often reference is made of a pick-up.
The invention now will be explained with reference to the drawing of some arbitrary embodiments to which the invention is not limited. In the drawing: